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Kidney Week

Abstract: SA-PO523

AKI Due to Methotrexate-Induced Crystal Nephropathy with Electron Microscopy

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical, Outcomes, and Trials

Authors

  • Contreras, Gabriel, University of Miami, Miami, Florida, United States
  • Abdalla, Aza, Jackson Memorial Hospital/University of Miami, Miami, Florida, United States
  • Amarapurkar, Pooja D., Jackson Memorial Hospital/University of Miami, Miami, Florida, United States
  • Thomas, David B., University of Miami, Miller School of Medicine, Miami, Florida, United States
Introduction

High dose methotrexate (MTX) (infusion of 1.5 to 8.0 gm/m2) is a key component of regimens for treatment of primary central nervous system lymphoma (PCNSL). 90% of MTX and its metabolites are excreted via the kidney. They are poorly soluble in acid pH and need intense hydration and alkalization of the urine (pH > 7) to reduce the risk of acute kidney injury (AKI) to less than 5%. Here, we present a case of AKI due to MTX-induced crystal nephropathy with by electron microscopy.

Case Description

A 53 years old male presented with frontal headaches. Imaging study followed by brain biopsy confirmed the diagnosis of PCNSL. Patient had normal baseline serum creatinine of 0.91 mg/dL prior to two infusions of high dose MTX 3.5 gm/m2 on 3/7/18 and 3/21/18. MTX and serum creatinine levels peaked at 12.3 mmol/L on 3/24/18 and 5.82 mg/dl on 3/28/18 respectively. Patient developed AKI in spite of maintaining intensive hydration, urine pH between 8 and 9 with the use of crystalloid solution of sodium bicarbonate and an adequate urine output of approximately 100 mL/hour. The urine sediment showed brownish crystals. Kidney biopsy done on 4/3/18, revealed light microscopy diffuse severe acute tubular epithelial cell injury (acute tubular necrosis, ATN) with tubular lumen MTX crystals also present by electron microscopy (image 1). After discontinuing MTX, the serum creatinine gradually improved to a level of 2.1 mg/dL on the day of discharge on 4/21/18.

Discussion

supersaturation is the initial step in crystallization of MTX in the renal tubular lumens, may occur despite maintaining adequate urine output and urine alkalization and leads to MTX-induced crystal nephropathy. We report a case of MTX-induced crystal nephropat, renal biopsy morphologic features of nephrotoxic ATN and MTX crystals both by light microscopy and electron microscopy.

IMAGE 1